Manufacture of artificial silk and like materials from viscose solutions



Patented May 4, 1 926.

WILL,IAH ron'rnn DREAJPER, or LONDON, ENGLAND.

muncrnan or an'rrrrcur.

Io Drawing.

To all whom it maycomem:

Be it known that I, WILLrAM PORTER DREAPER, a British subject, reslding at 27 Willow Road, Hampstead, London, N. W. 3, England, have invented new and useful Improvements in the Silk and like Materials from Viscose Solutions, of which the following is a specification. In the manufacture of artificial silk, staple fibre and like ,roducts by the viscoseprocess, it is usua to" use a precipitating bath which consists of a salt such as sodium sulphate to whicha certain amount of sulphuric acid has been added, and to add certain other substances such as glucose or zinc chloride or both to improve the spinning qualities and facilitate working conditions, but generally speaking the filaments so produced have not been spun below a size of, say, six to eightdeniers from such a bath owing to difficulties being met within practice, and as a resultthe general run of filaments producedcommercrally by the viscose process have approximated to those instanced. Such acid baths as have been men'- tioned have been used of varying strengths of acid and added salt, and in some cases it has been suggested that very concentrated solutions should be utilized. Such practice introduces difficulties which have generally acted against the use of such solutions.

I now find that the finerfilaments can be easily produced even down to from two to four deniers in size without material increase in cost or difliculty in manufacture by introducing into the acid-salt precipitating bath a relatively small amount of ammonium sulphate or other salt of ammonia, when it has been observed that the actual formation of the filaments in the bath is so regulated that finer filaments can be drawn 0 than in the ordinary bath, and yet finall a filament in strand is produced which wi l readily stand the strain of subsequent o rations of winding and treatment to w ich they are ordinarily subjected. In fact spin ning operations are so improved that such be more easily produced in this bath than the coarser ones in an ordinary acid-salt bath.

To illustrate'this invention the following example is glllven. The precipitatin bath is made up wit say, twenty per cent 0 sodium sulphate and from seven to fourteen per cent Application filed October 18, 1923. Serial No.

Manufacture of Artificial is used or the said bath funnel is a o solutions in an srm: am) LIKE mammals rnom vrscosn somrrrons.

of sulphuric acid and to this bath is added from one per cent to eight per cent of ammonium sulphate. three to six per cent of ammonium sulphate is piarticularly useful and when such a bath 15 between 30 C. and 0., but preferably about 42 (1., fine filaments can be easily spun at a rate of fifty metres per minute or more from holes even up to 0.15 mm. diameter, Such results indicate that inthe pres ence of such relatively small amounts of ammoniumsalt in the strength of the bath indicated considerably more extension of the forming filaments is possible when this salt is added to an acid bath of the composition A bath containing from ept at a temperature which may vary named. This bath may also be used in suit-' I ble strength in the 'guider funnel when sucn may be immediately followed by a treatment with any other selected solution or even water and then simultaneously passed to and spun into a centrifugal box or collected ona bobbin in the well'known manner, or otherwise treated or collected as hitherto.

With this addition to-the bath it is not organic substances to the bath. or any other addition other than the normal constituents of the bath as mentioned. In addition, and where a se arate treatment in the guider ted a certain amount of the ammonium sa t can be recovered by known .means from the guider funnel solution or the wash-waters. 1 I claim: 1. The'manufacture' like products of fine filaments from viscose acid-salt bath of relatively low concentration characterized by containing twenty-two per cent of sodium sulphate,

seven to fourteen per cent sulphuric acid, to which is added about five per cent Spot being less than oneper cent-or more t an eight per cent) of ammonium sulphate, the send filaments being fifty metres per minute or more. '2. The manufacture of artificial silk and like products of fine filaments from viscose solutions in an acid-salt bath of relatively low concentration characterized by containing twenty-two per cent sodium sulphate, twelve per cent sulphuric acid, to which is added SIX per cent ammonium sulphate. 3. The manufacture of artificial silk'and necessary to' add glucose 'or other similar 5i artificial silk and drawn off at a speed of w-A as like products of fine filaments from viscose solutions in an acid-salt bath of relatively low concentration characterized by said bath containing twenty-two per cent sodium sul-- 5 phate or an equivalent acting sulphate, or an equivalent portion of the same which will enable such. fine filaments to be produced, 

